| 12 Dec 2025
Contrasting impact of different Mediterranean cyclones on the hydrological cycle and ocean heat content
Abstract. Mediterranean cyclones (MCs) play a crucial role in the Mediterranean hydrological cycle (MHC), driving up to 70 % of precipitation and 50 % of evaporation totals, and larger fractions of their extremes. Therefore, regional sensitivity to warming is often associated with long-term changes of MCs. These may lead to regional climate feedback through pathways linked directly or indirectly to the MHC: from decreasing cloud cover and precipitation to increased water-vapor uptake. However, the ability of MCs to generate coherent climate feedback is under ongoing debate. Moreover, given the large diversity of processes driving MCs, the role of each in the MHC and their variability remains unexplored. Our recent process-based MC classification allows the breakdown of MC’s contribution to the MHC under different dominant cyclogenetic processes. Based on 1-hourly ECMWF ERA5 reanalysis data (1979–2020), 3190 MC tracks are analyzed. We first quantify the total contribution of MCs to the MHC following the cyclone tracks. We analyze the spatial and temporal patterns of the annually accumulated cyclone-induced precipitation (P) and surface evaporation (E). The process-based classification allows the quantification of independent contributions from various cyclone drivers to cyclone-induced P and E and their long-term trends. The results show that the overall annual P-E residual associated with MCs is positive but decreases over time, losing ~0.5 mm/yr per year. The classification reveals opposing roles and long-term trends in the annual contributions of each cyclone driver, shifting the balance between cyclone-induced P and E from P-dominated towards E-dominated MCs. These changes are primarily due to reduced precipitation associated with double-jet MCs and daughter cyclones and increased evaporation associated with thermal lows (−0.2 mm/year, each), alternately driven by changes in frequency and/or flux intensities of specific cyclone drivers. Mainly, a sharp rise in frequency affects heat lows, while double-jet cyclones are mostly affected by decreasing precipitation rates. The downward impact of MCs on the Mediterranean Sea heat content also varies sharply between MC types: while MCs generally draw heat from the Mediterranean, certain MC types have the opposing effect, adding further heat. Beyond providing a framework for follow-up analysis of MC impact on the MHC in future climate simulations, the results highlight the independent and opposing contributions of different MC drivers to the Mediterranean heat content, enhancing our understanding of their dynamic response to warming and its impact on society.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Weather and Climate Dynamics.
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A review of “Contrasting impact of different Mediterranean cyclones on the hydrological cycle and ocean heat content” by Yonatan Givon et al. (2025)
Recommendation: Minor revisions
Givon et al., (2025) leverages previous work on identifying distinct categories of Mediterranean cyclones to assess how these cyclones impact precipitation and evaporation rates across the Mediterranean basin. Through this analysis, the trend of precipitation and evaporation rates are found to differ across cyclone types, which can then inform future work on regional climate risk.
The figures and research are all high caliber and the paper flows as a coherent scientific story, for which I commend the authors. My main critique for this paper is with how much contextual information is not included to understand the discussion of this paper. I find this information necessary to interpret some of the main findings of the paper and to understand some of the points in the discussion section of the paper.
Main/general comments
When describing some of your results, you allude to results from your previous paper discussing the clustering of your cyclones. Often there are references to seasonality or large-scale flow configurations that I cannot deduce without examining your previous paper. An examples where I wanted additional context is lines 244–257 (referencing clusters as summer or winter, or the double jet configuration not shown in this paper). I think figures 3 and 6 from Givon et al., (2024a), as well as a brief summary of the results of these figures, should be incorporated into the paper or included in the supplemental information to give the reader more context on your previous work.
I also found that several points included in the discussion were not properly supported by the research presented earlier in the text. Some examples include:
I can understand the desire to place this work into a larger context, but as it stands currently, I find many of the claims related to the results of Givon et al., (2024a) rather than your current paper. I think these instances need to be rewritten to explicitly link back to your previous work.
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